The present invention relates to a horizontal deflection high-voltage circuit suitable for use in a display apparatus using a cathode ray tube (CRT).
In the field of display apparatus such as a display unit for a computer of which a high picture quality is required, it has been studied to use a system in which the horizontal deflection circuit is integrated with the high voltage circuit. As to the integrated horizontal deflection and high-voltage circuit, there is, for example, an art disclosed in Japanese Laid-open Patent Publication No. 58-138179. The horizontal deflection high-voltage circuit disclosed in this reference used a diode modulation horizontal deflection circuit and was capable of controlling the high voltage to be kept constant regardless of variations in the high-voltage load and also capable of keeping the amplitude of the horizontal deflection current constant. In such an example of known art, control was made such that changes in the voltage of the high-voltage section was detected by a deviation detection circuit and the flyback transformer and the deflection current were regulated according to the output signal of the deviation detection circuit.
In the prior art, as described above, the circuit was organized such that the output signal of the deviation detection circuit was input to the input terminal of the flyback transformer, whereby the high voltage output from the flyback transformer was controlled to be kept constant, and at the same time, the output signal of the deviation detection circuit was converted into a signal for regulating the horizontal deflection current.
Therefore, it was required in the prior art that, when the output signal of the deviation detection circuit was inpout to the circuit for controlling the horizontal deflection current, the output signal of the deviation detection circuit had to be adjusted by a volume control or the like. For this reason, there have been in the prior art problems of a considerable time required for the adjustments by means of the volume control or the like and resultant irregularity of adjustment and deterioration in the performance due to aging, and such problems have not been paid much attention.